I took all these photos at Bolsa Chica Ecological Reserve in Huntington Beach, California on 2018-04-20.
I assume the first is a Scaup, but I'm not sure if its a Greater or a Lesser.
The last two were taken a couple hours apart, so I'm not sure whether they are same individual or not. I assume they are Mergansers, but I'm not sure if they are Common or Red-breasted.
Any help would be appreciated.